1. Field of the Invention
The present invention relates to a compression release engine brake unit and, more particularly, to a compression release engine brake unit, which includes an oil outlet passage formed in a socket brake, which stores engine brake oil, and a reset member opening/closing the outlet passage, such that the reset member discharges the engine brake oil by opening the oil outlet passage in response to the rotation of a rocker arm during engine braking and, thereby, the engine brake restores the initial state.
2. Description of Related Art
Engine braking generally refers to the act of slowing down a vehicle by down-shifting to a lower transmission gear. In the engine braking, however, an excessive amount of load is applied to respective parts of an engine since a transmission is down-shifted. This may cause drawbacks such as reduced engine lifetime.
A compression release engine brake was introduced in order to solve the foregoing problem. The compression release engine brake forcibly opens an exhaust valve at the end of compression stroke in order to avoid power stroke and to thereby maximize the effect of engine braking.
FIG. 1 is a graph illustrating a change in the amount of valve lift when a conventional compression release engine brake is actuated.
In a conventional compression release engine brake unit, when the engine brake is actuated, engine brake oil is fed into a socket brake so that a piston moves up and down under the pressure of the engine brake oil. Then, a gap between a valve and a rocker arm can be maintained zero (0), and the exhaust valve can be forcibly opened at the end of compression stroke.
The socket brake allows opening the exhaust valve at the end of compression stroke to slow down a vehicle, thereby maximizing the effect of engine braking. However, as shown in FIG. 1, the engine brake oil is not discharged from the socket brake once introduced to the latter. This causes a problem in that the oil pressure formed inside the socket brake may open the exhaust valve more, thereby bringing the valve into contact with the piston and weakening the performance of the engine brake.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.